Conventionally, it has been done to form a character or an image on a transfer-receiving material by using a thermal transfer system. As the thermal transfer system, a thermal sublimation transfer system and a thermal melting transfer system are being widely used. Of these, the thermal sublimation transfer system is a system using a sublimable dye as a color material, where the dye in the sublimable dye layer on a thermal transfer sheet is transferred onto a transfer-receiving material such as thermal transfer image-receiving sheet by using a heating device such as thermal head or laser beam, which is controlled to generate heat according to image information, and an image is thereby formed. In this thermal sublimation transfer system, the amount of the dye transferred can be controlled on a dot basis by overheating in an extremely short time. Thanks to use of a dye as the color material, the thus-formed image is very clear and has excellent transparency and therefore, the image obtained is excellent in the half-tone reproducibility and gradation and becomes an extremely high-definition image. Thus, a high-quality image comparable to a full-color silver-salt photograph can be obtained. Moreover, as compared with the normal silver-salt photographic image forming system, the thermal sublimation transfer system has many advantages such as being a dry process, capable of visualizing an image directly from digital data, and easy to duplicate.
Generally, in a thermal transfer image-receiving sheet, at least a dye image-receiving layer (receptive layer) and a heat-insulating layer are formed on a support. As the resin for forming the receptive layer, a vinyl chloride-based resin is used, because this is excellent in dyeability with a dye and releasability and causes no abnormal transfer such as fusion bonding between the thermal transfer sheet and the thermal transfer image-receiving sheet during thermal transfer. At the time of coating a vinyl chloride-based resin on a base material sheet to form a receptive layer, the resin has been conventionally used by dissolving it in an organic solvent.
However, it is concerned that the working environment is worsened by the use of an organic solvent.
To eliminate this concern, a method of forming a receptive layer by using a vinyl chloride-based resin latex without use of an organic solvent is being widely studied (Patent Document 1).
Nevertheless, a satisfactory image is not obtained by a thermal sublimation transfer image-receiving sheet using the vinyl chloride-based resin latex.
In this way, a vinyl chloride-based resin latex giving a thermal sublimation transfer image-receiving sheet capable of excellent image formation is not known.